what can i do when i see a dog locked in a hot car ?

what is the policy?  i had to confront a couple who locked their dog in the car during July when it was 105 degrees. 

Last year, an "elite" horsewoman's mother locked a dog up in her subaru at Meadowood. i tried calling for help, but got referred from non emergency to county humane society. they almost locked me up for harrasment because i followed her and told her she couldn't leave her dog in that hot car!  the response... oh, it's just for a few minutes, stop bothering us.